The present invention relates to the forming of fuel rails, and more particularly to forming fuel rails employing a hydroforming process.
Vehicles today typically employ fuel injectors to feed fuel to an engine. In particular, there are some engines that operate with direct fuel injection. In a fuel system for a direct injection engine, the fuel is transferred to the combustion chambers (cylinders) under high pressure in order to overcome the pressure within the combustion chambers. A typical high pressure fuel rail includes a hollow conduit having a plurality of U-shaped blocks provided thereon. Each of the blocks has a recessed fuel injector port formed therein to receive a portion of a fuel injector, and also typically includes a mounting member so that the block functions as a mounting bracket as well. These fuel rail assemblies have commonly been manufactured by forming a plurality of fuel holes in the conduit, then brazing or otherwise securing each of the blocks about a respective one of the holes. Although effective, this process is somewhat time consuming and inefficient. Further, it is desirable to avoid the concerns of fuel rails warping during the brazing process in order to avoid the requirement of machining after brazing. Additionally, it is desirable to reduce the chance of creating a leak path for the fuel at the brazing locations.
Thus, it is advantageous to have a fuel rail assembly and a method for manufacturing the fuel rail assembly that overcomes the drawbacks of the prior art.
This invention relates to an improved method for manufacturing a fuel rail assembly for use with internal combustion engines employing fuel injectors. In particular, the invention relates to an improved high pressure fuel rail assembly for use with direct injection engines.
In its embodiments, the present invention contemplates a method of manufacturing a fuel rail assembly comprising the steps of: providing a hollow tube and a plurality of blocks, wherein each of the blocks has a passage formed therethrough and a recessed fuel injector port, inserting the tube into the passages in the blocks; mounting the tube and blocks in a hydroforming die, and positioning the blocks in desired positions relative to the tube; supplying pressurized fluid to the interior of the tube, causing the tube to expand outwardly into engagement with the blocks; and piercing holes through the tube within each of the blocks to provide fluid communication with the associated recessed fuel injector ports.
The present invention further contemplates a method of manufacturing a fuel rail assembly comprising the steps of: providing a hollow tube and a plurality of blocks, wherein each of the blocks has a passage formed therethrough and a recessed fuel injector port; providing at least one seal; inserting the tube into the passages in the blocks; locating the seal between the tube and at least one of the passages; mounting the tube and blocks in a hydroforming die, and positioning the blocks in desired positions relative to the tube; and supplying pressurized fluid to the interior of the tube, causing the tube to expand outwardly into engagement with the seal and the blocks.
The present invention also contemplates a fuel injector assembly formed by one of the above noted methods.
Accordingly, an object of the present invention is to form an improved fuel rail assembly employing a hydroforming process.
An advantage of the present invention is that the fuel rail assembly can be formed more efficiently.
Another advantage of the present invention is that the fuel rail assembly formed is less likely to be warped or have potential fuel leak paths.